T cells belonging to the y?-lineage have been shown to serve a unique and critical role within the immune system. y? T cells are widely distributed throughout mucosal and epithelial cell-rich tissues and are an important early source of IL-17 in response to a number of pathogens, recruiting granulocytes to the site of inflammation. However, how y? T cells acquire the ability to respond as IL-17-producing cells prior to antigen exposure remains unclear. Additionally, how y? T cells become specified and assigned to IL-17 or interferon-y (IFNy) effector fates remains to be fully elucidated. Recent evidence supports the notion that T cell receptor (TCR) signals affect the type of effector function that y? T cells adopt within the thymus, such as becoming interferon-y (IFNy), IL-4 or IL-17 producing cells. Given the critical importance of Notch signaling throughout T cell differentiation, we hypothesized that the final differentiation and effector function selection by y? T cells is guided by Notch receptor-ligand interactions, which influence the generation of IFNy vs. IL-17 producing cells. We will take advantage of the in vitro model system that we have previously established to elucidate the roles for TCR, Notch and cytokine signals in determining the final effector function of y? T cells, and gain insight into the molecular basis for these selections by assembling global gene regulatory networks. Our aims are: 1) to address the role of Notch receptor signaling in y? T cell effector differentiation; 2) to address the role of cytokine receptor signaling in y? T cell effector differentiation; and, 3) to determine the role of E-proteins, together with Notch and cytokine signals, in specifying y? T cell effector function. Taken together, our joint experimental approach and findings will provide important insights into the molecular processes controlling y? T cell development and function, which would not be possible without the combined expertise provided by all members of this program.